Apparatus for controlling operation of compressors

ABSTRACT

An apparatus for controlling an operation of compressors includes a single microcomputer for calculating stroke estimate values of multiple compressors based on voltage and current values applied to the multiple compressors, and generating a plurality of switching control signals for independently controlling a voltage applied to the multiple compressors based on the calculated stroke estimate values and pre-set stroke reference values; and switching devices each installed in the multiple compressors, for independently controlling the voltage applied to the multiple compressors according to the plurality of switching control signals. Since the reciprocating compressors are controlled by a single apparatus, costs and power consumption can be reduced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compressor and, more particularly, to an apparatus for controlling an operation of a compressor.

2. Description of the Prior Art

In general, a reciprocating compressor (hereinafter, for simplicity, referred to as “reciprocating motor compressor”), which is operated by a linearly reciprocating electric motor without a crank shaft for converting a rotational motion to a linear motion, has less friction loss, and thus, can provide a higher compression efficiency than other compressors.

When the reciprocating motor compressor is used for a refrigerator or an air-conditioner, a compression ratio of the compressor can be varied to control the cooling capacity by varying a stroke voltage applied to the reciprocating motor of the compressor.

The conventional controlling of a reciprocating motor compressor will now be described with reference to FIG. 1.

FIG. 1 is a block diagram showing the construction of an apparatus for controlling an operation of a reciprocating compressor in accordance with a conventional art.

As shown in FIG. 1, the apparatus for controlling an operation of the reciprocating compressor includes: a voltage detector 14 for detecting a voltage applied to a reciprocating compressor 13 as a stroke of the reciprocating compressor 13 is varied; a current detector 12 for detecting a current applied to the reciprocating compressor 13 as the stroke is varied; a microcomputer 15 for calculating a stroke based on the voltage value detected by the voltage detector 14 and the current value detected by the current detector 12, comparing the calculated stroke with a stroke reference value, and generating a switching control signal according to the comparison result; and a power supply unit 11 for supplying a stroke voltage to the reciprocating compressor 13 by controlling ON/OFF of AC power supplied to the reciprocating compressor 13 with an internal triac Tr1 according to the switching control signal generated by the microcomputer 15. Herein, the reciprocating compressor 13 varies the stroke upon receiving the stroke voltage provided to an internal motor (not shown) according to the stroke reference value previously set by a user, and reciprocally moves an internal piston (not shown).

The apparatus for controlling an operation of a reciprocating compressor in accordance with the conventional art operates as follows.

First, when a voltage is supplied to the internal motor according to the stroke reference value as set by the user, the reciprocating compressor 13 varies the stroke and reciprocally moves the piston. Herein, the stroke means a distance along which the piston of the reciprocating compressor 13 is reciprocally moved.

The turn-on duration of the triac (Tr1) of the power supply unit 11 is lengthened by the switching control signal outputted from the microcomputer 15, and accordingly, the AC power is supplied to the reciprocating compressor 13 to drive the reciprocating compressor 13. At this time, the voltage detector 14 and the current detector 12 detect each value of the voltage and the current applied to the reciprocating compressor 13, respectively, and output the detected voltage and current values to the microcomputer 15.

The microcomputer 15 calculates a stroke estimate value of the reciprocating compressor 13 based on the voltage and current values respectively detected by the voltage detector 14 and the current detector 12, compares the calculated stroke estimate value with the stroke reference value, and generates a switching control signal according to the comparison result. For example, if the calculated stroke estimate value is smaller than the stroke reference value, the microcomputer 15 outputs a switching control signal for lengthening the turn-on duration of the triac (Tr1) to the power supply unit 11 to increase the stroke voltage supplied to the reciprocating compressor 13.

If, however, the calculated stroke estimate value is greater than the stroke reference value, the microcomputer 15 outputs a switching control signal for shortening the turn-on duration of the triac Tr1 to the power supply unit 11 to reduce the stroke voltage supplied to the reciprocating compressor 13.

The microcomputer 15 can more accurately calculate the stroke estimate value (X) of the reciprocating compressor 13 by substituting the detected current value, the detected voltage value and a parameter of an internal motor (not shown) of the reciprocating compressor 13 to equation (1) shown below: $\begin{matrix} {X = {\frac{1}{\alpha}{\int{\left( {V_{M} - {Ri} - {Li}} \right){\mathbb{d}t}}}}} & (1) \end{matrix}$ wherein ‘R’ is a motor resistance value of the reciprocating compressor, ‘L’ is a motor inductance value of the reciprocating compressor, ‘α’ is a motor constant of the reciprocating compressor, V_(M) is the value of the voltage applied to the motor of the reciprocating compressor, ‘i’ is the value of the current applied to the motor of the reciprocating compressor, and {overscore (i)} is a time variation rate of the current applied to the motor of the reciprocating compressor, namely, a differential value (di/dt) of ‘i’.

FIG. 2 is a schematic view showing the construction of a refrigerator having two reciprocating compressors in accordance with a conventional art.

As shown in FIG. 2, a reciprocating compressor is installed in both a refrigerating chamber and a freezing chamber of a refrigerator, to independently control a temperature of the refrigerating chamber and a temperature of the freezing chamber. However, in the conventional art, when the two reciprocating compressors are applied to the refrigerator, two apparatus for controlling an operation of the reciprocating compressors are required to control the two reciprocating compressors. This results in an increase in costs and power consumption.

U.S. Pat. No. 6,644,943 issued on Nov. 11, 2003 also discloses a conventional reciprocating compressor.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an apparatus for controlling an operation of compressors capable of reducing costs and power consumption by controlling two reciprocating compressors by using the single apparatus.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for controlling an operation of compressors including: a single microcomputer for calculating stroke estimate values of multiple compressors based on voltage and current values applied to the multiple compressors, and generating a plurality of switching control signals for independently controlling a voltage applied to the multiple compressors based on the calculated stroke estimate values and pre-set stroke reference values; and switching devices each installed in the multiple compressors, for independently controlling the voltage applied to the multiple compressors according to the plurality of switching control signals.

To achieve the above object, there is also provided an apparatus for controlling an operation of compressors including: a first voltage detector for detecting a voltage applied to a first reciprocating compressor; a first current detector for detecting a current applied to the first reciprocating compressor; a second voltage detector for detecting a voltage applied to the second reciprocating compressor; a second current detector for detecting a current applied to the second reciprocating compressor; a single microcomputer for calculating a first stroke estimate value of the first reciprocating compressor based on the voltage value of the first voltage detector and the current value of the first current detector, comparing the first stroke estimate value with a pre-set first stroke reference value, generating a first switching control signal according to the comparison result, calculating a second stroke estimate value of the second reciprocating compressor based on the voltage value of the second voltage detector and the current value of the second current detector, comparing the second stroke estimate value with a pre-set second stroke reference value, and generating a second switching control signal according to the comparison result; a first switching device for controlling a voltage applied to the first reciprocating compressor according to a first switching control signal of the single microcomputer; and a second switching device for controlling a voltage applied to the second reciprocating compressor according to the second switching control signal of the single microcomputer.

To achieve the above object, there is also provided an apparatus for controlling an operation of compressors applied to a refrigerator including: a first voltage detector for detecting a voltage applied to a first reciprocating compressor installed in a refrigerator; a first current detector for detecting a current applied to the first reciprocating compressor; a second voltage detector for detecting a voltage applied to the second reciprocating compressor installed in the refrigerator; a second current detector for detecting a current applied to the second reciprocating compressor; a single microcomputer for calculating a first stroke estimate value of the first reciprocating compressor based on the voltage value of the first voltage detector and the current value of the first current detector, comparing the first stroke estimate value with a pre-set first stroke reference value, generating a first switching control signal according to the comparison result, calculating a second stroke estimate value of the second reciprocating compressor based on the voltage value of the second voltage detector and the current value of the second current detector, comparing the second stroke estimate value with a pre-set second stroke reference value, and generating a second switching control signal according to the comparison result; a first triac for controlling a voltage applied to the first reciprocating compressor according to a first switching control signal of the single microcomputer; and a second triac for controlling a voltage applied to the second reciprocating compressor according to the second switching control signal of the single microcomputer, wherein the microcomputer outputs a first switching control signal for lengthening a turn-on period of the first triac to the first triac to increase a voltage applied to the first reciprocating compressor when the first stroke estimate value is smaller than the pre-set first stroke reference value, outputs a first switching control signal for shortening the turn-on period of the first triac to the first triac to reduce the voltage applied to the first reciprocating compressor when the first stroke estimate value is larger than the pre-set first stroke reference value, outputs a second switching control signal for lengthening a turn-on period of the second triac to the second triac to increase a voltage applied to the second reciprocating compressor when the second stroke estimate value is smaller than the pre-set second stroke reference value, and outputs a second switching control signal for shortening the turn-on period of the second triac to the second triac to reduce the voltage applied to the second reciprocating compressor when the second stroke estimate value is larger than the pre-set second stroke reference value.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1 is a block diagram showing the construction of an apparatus for controlling an operation of a reciprocating compressor in accordance with the conventional art;

FIG. 2 is a schematic view showing the construction of a refrigerator having two reciprocating compressors in accordance with the conventional art; and

FIG. 3 is a block diagram showing the construction of a single apparatus for controlling an operation of two reciprocating compressors applied to a refrigerator in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An apparatus for controlling an operation of compressors capable of reducing costs and power consumption by controlling two compressor applied to a refrigerator.

FIG. 3 is a block diagram showing the construction of a single apparatus for controlling an operation of two reciprocating compressors applied to a refrigerator in accordance with the present invention.

As shown in FIG. 3, the apparatus for controlling an operation of the compressors in accordance with the present invention includes a first voltage detector 104 for detecting a voltage applied to a first reciprocating compressor 103 installed in a refrigerator; a second voltage detector 108 for detecting a voltage applied to a second reciprocating compressor 109 installed in the refrigerator; a first current detector 102 for detecting a current applied to the second reciprocating compressor 109; a second current detector for detecting a current applied to the second reciprocating compressor 109; a microcomputer 105 for calculating a first stroke estimate value of the first reciprocating compressor 103 based on the voltage value of the first voltage detector 104 and the current value of the first current detector 103, comparing the first stroke estimate value with a pre-set first stroke reference value, generating a first switching control signal according to the comparison result, calculating a second stroke estimate value of the second reciprocating compressor 109 based on the voltage value of the second voltage detector 108 and the current value of the second current detector 106, comparing the second stroke estimate value with a pre-set second stroke reference value, and generating a second switching control signal according to the comparison result; a first triac 101 for controlling a voltage applied to the first reciprocating compressor 103 according to a first switching control signal of the single microcomputer 105; and a second triac 107 for controlling a voltage applied to the second reciprocating compressor 109 according to the second switching control signal of the microcomputer 105.

The operation of the apparatus for controlling an operation of the two reciprocating compressors applied to the refrigerator in order to reduce fabrication costs and power consumption will be described as follows.

First, the first voltage detector 104 detects a voltage applied to the first reciprocating compressor 103 and outputs the detected voltage value to the microcomputer 105. The second voltage detector 108 detects a voltage applied to the second reciprocating compressor 109 and outputs the detected voltage value to the microcomputer 105.

The first current detector 102 detects a current applied to the first reciprocating compressor 103 through a resistor R1 and outputs the detected current value to the microcomputer 105. The second current detector 106 detects a current applied to the second reciprocating compressor 109 through a resistor R2 and outputs the detected current value to the microcomputer 105.

The microcomputer 105 calculates a first stroke estimate value of the first reciprocating compressor 103 based on the voltage and current values detected respectively by the first voltage detector 104 and the first current detector 102, compares the first stroke estimate value with a pre-set first stroke reference value, and generates a first switching control signal according to the comparison result. For example, if the first stroke estimate value is smaller than the pre-set first stroke reference value, the microcomputer 105 outputs a first switching control signal for lengthening a turn-on period of the first triac 101 to the first triac 101 to increase a voltage (stroke voltage) supplied to the first reciprocating compressor 103.

If, however, the first stroke estimate value is larger than the pre-set first stroke reference value, the microcomputer 105 outputs a first switching control signal for shortening the turn-on period of the first triac 101 to the first triac 101 to reduce the stroke voltage supplied to the first reciprocating compressor 103.

Also, the microcomputer 105 calculates a second stroke estimate value of the second reciprocating compressor 109 based on the voltage and current values detected respectively by the second voltage detector 108 and the second current detector 106, compares the second stroke estimate value with a pre-set second stroke reference value, and generates a second switching control signal according to the comparison result. For example, if the second stroke estimate value is smaller than the pre-set second stroke reference value, the microcomputer 105 outputs a second switching control signal for lengthening a turn-on period of the second triac 107 to the second triac 107 to increase a stroke voltage supplied to the second reciprocating compressor 109.

If, however, the second stroke estimate value is larger than the pre-set second stroke reference value, the microcomputer 105 outputs a second switching control signal for shortening the turn-on period of the second triac 107 to the second triac 107 to reduce the stroke voltage supplied to the second reciprocating compressor 109.

Accordingly, the first and second triacs 101 and 107 are switched by the first and second switching control signals of the microcomputer 105 to vary the voltage applied to the first and second reciprocating compressors 103 and 109 to separately control cooling air supplied to a refrigerating chamber and a freezing chamber. Namely, since the single microcomputer independently controls the two compressors based on the voltage values and the current values applied to the two compressors, fabrication costs and power consumption of the operation controlling apparatus can be reduced.

As so far described, the apparatus for controlling an operation of the compressors in accordance with the present invention has the following advantages.

By controlling the two compressors applied to the refrigerator by the single operation controlling apparatus, fabrication costs and power consumption can be reduced. Namely, since the two compressors applied to the refrigerator are separately controlled by the microcomputer, the fabrication cost and power consumption of the operation controlling apparatus can be reduced.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims. 

1. An apparatus for controlling an operation of compressors comprising: a single microcomputer for calculating stroke estimate values of multiple compressors based on voltage and current values applied to the multiple compressors, and generating a plurality of switching control signals for independently controlling a voltage applied to the multiple compressors based on the calculated stroke estimate values and pre-set stroke reference values; and switching devices each installed in the multiple compressors, for independently controlling the voltage applied to the multiple compressors according to the plurality of switching control signals.
 2. An apparatus for controlling an operation of compressors comprising: a first voltage detector for detecting a voltage applied to a first reciprocating compressor; a first current detector for detecting a current applied to the first reciprocating compressor; a second voltage detector for detecting a voltage applied to the second reciprocating compressor; a second current detector for detecting a current applied to the second reciprocating compressor; a single microcomputer for calculating a first stroke estimate value of the first reciprocating compressor based on the voltage value of the first voltage detector and the current value of the first current detector, comparing the first stroke estimate value with a pre-set first stroke reference value, generating a first switching control signal according to the comparison result, calculating a second stroke estimate value of the second reciprocating compressor based on the voltage value of the second voltage detector and the current value of the second current detector, comparing the second stroke estimate value with a pre-set second stroke reference value, and generating a second switching control signal according to the comparison result; a first switching device for controlling a voltage applied to the first reciprocating compressor according to a first switching control signal of the single microcomputer; and a second switching device for controlling a voltage applied to the second reciprocating compressor according to the second switching control signal of the single microcomputer.
 3. The apparatus of claim 2, wherein the first and second switching devices are a triac, respectively.
 4. The apparatus of claim 2, wherein when the first stroke estimate value is smaller than the pre-set first stroke reference value, the microcomputer outputs the first switching control signal for lengthening a turn-on period of the first triac to the first triac.
 5. The apparatus of claim 4, wherein when the first stroke estimate value is larger than the pre-set first stroke reference value, the microcomputer outputs the first switching control signal for shortening the turn-on period of the first triac to the first triac.
 6. The apparatus of claim 5, wherein when the second stroke estimate value is smaller than the pre-set second stroke reference value, the microcomputer outputs the second switching control signal for lengthening a turn-on period of the second triac to the second triac.
 7. The apparatus of claim 6, wherein when the second stroke estimate value is larger than the pre-set second stroke reference value, the microcomputer outputs the second switching control signal for shortening the turn-on period of the second triac to the second triac.
 8. The apparatus of claim 7, wherein the elements are installed in a refrigerator.
 9. An apparatus for controlling an operation of compressors applied to a refrigerator comprising: a first voltage detector for detecting a voltage applied to a first reciprocating compressor installed in a refrigerator; a first current detector for detecting a current applied to the first reciprocating compressor; a second voltage detector for detecting a voltage applied to the second reciprocating compressor installed in the refrigerator; a second current detector for detecting a current applied to the second reciprocating compressor; a single microcomputer for calculating a first stroke estimate value of the first reciprocating compressor based on the voltage value of the first voltage detector and the current value of the first current detector, comparing the first stroke estimate value with a pre-set first stroke reference value, generating a first switching control signal according to the comparison result, calculating a second stroke estimate value of the second reciprocating compressor based on the voltage value of the second voltage detector and the current value of the second current detector, comparing the second stroke estimate value with a pre-set second stroke reference value, and generating a second switching control signal according to the comparison result; a first triac for controlling a voltage applied to the first reciprocating compressor according to a first switching control signal of the single microcomputer; and a second triac for controlling a voltage applied to the second reciprocating compressor according to the second switching control signal of the single microcomputer, wherein the microcomputer outputs a first switching control signal for lengthening a turn-on period of the first triac to the first triac to increase a voltage applied to the first reciprocating compressor when the first stroke estimate value is smaller than the pre-set first stroke reference value, outputs a first switching control signal for shortening the turn-on period of the first triac to the first triac to reduce the voltage applied to the first reciprocating compressor when the first stroke estimate value is larger than the pre-set first stroke reference value, outputs a second switching control signal for lengthening a turn-on period of the second triac to the second triac to increase a voltage applied to the second reciprocating compressor when the second stroke estimate value is smaller than the pre-set second stroke reference value, and outputs a second switching control signal for shortening the turn-on period of the second triac to the second triac to reduce the voltage applied to the second reciprocating compressor when the second stroke estimate value is larger than the pre-set second stroke reference value. 